Purlins Metal Roof Spacing

An engineer will use a load chart in order to determine the spacing between metal purlins.

Purlins metal roof spacing. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Spacing for purlins on a standard load most designs call for purlin placement at five foot intervals. The typical spacing standards for residential and commercial buildings are about 1 to 2 foot. Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes.

Screw line spacing for metal roofing over metal purlins. Once the purlin spacing is determined then the metal roofing panels are typically attached to every line of purlins. Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. For 2x6s purlins the posts are spaced in 6 feet distance.

The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. If the space between posts is greater than 8 feet then brace is needed to avoid buckling. By the standard the most used placement of purlin span for metal roof is five foot intervals. This will depend upon the type of panel that is used and the thickness of the steel.

Purlins are 2 by 4 feet and are installed much like metal roofing. For 2x4s purlins the posts are spaced in 4 feet distance. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig.

Do all roofing projects require purlins. The spacing of purlins on roofs and girts on wall is usually 4 to 6 ft. Installation of pole barn purlins. Edit answer for another 41 minute you need to check the installation instructions from the manufacturer depending on whether the purlins firring strips are 1x or 2x material and how wide thickness metal gage of roofing steel or aluminum type of seams design wind and snow loading whether designed to be walked on or not etc i have seen it vary from as little as 4 inches clear gap between firring strips on lightweight aluminum to as much as 4 feet on very heavy gage steel.

Metal roof purlins are installed horizontally under metal roofs. Standard gage are generally used for roofing. Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet.

For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. Numbers 20 and 22 u s. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

Fyi we run purlins on 3 5 feet on center depending on size of purlin.